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Left or right-wing? Brain’s disgust response tells all

By Dan Jones

THE way your brain reacts to a single disgusting image can be used to predict whether you lean to the left or the right politically.

Several studies have probed the emotions of people along the political spectrum, and found that disgust in particular is tightly linked to political orientation. People who react strongly to disgusting images are more likely to sit on the political right and show concern for what they see as bodily and spiritual purity. They tend to oppose abortion and gay marriage, for example. But how ingrained is it?

A team led by Read Montague, a neuroscientist at Virginia Tech in Roanoke, recruited 83 volunteers and performed fMRI brain scans on them as they looked at a series of 80 images that were either pleasant, disgusting, threatening or neutral. Participants rated the emotional impact of the images and completed questionnaires that assessed whether they were liberal, moderate or conservative.

The brain-imaging results were fed into an algorithm that compared the whole-brain responses of liberals and conservatives when looking at disgusting images versus neutral ones. For both political groups, the algorithm was able to pick out distinct patterns of brain activity triggered by the disgusting images.

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And even though the two groups consciously reported similar emotional reactions to the images, the specific brain regions involved and their patterns of activation differed consistently between them – so much so that they represent a neural signature of political leaning (Current Biology, doi.org/ws9).

Montague says they can predict with 95 per cent accuracy where a person is on the liberal-conservative spectrum just by showing them one picture. Darren Schreiber of the University of Exeter, UK, says the combination of whole-brain analysis with a learning algorithm marks a step forward.

This article appeared in print under the headline “Brain’s disgust response points to political view”